Request new access token using refresh token in username-password grant in Spring Security OAuth2

Question

We're using the username-password grant to obtain an access token from our auth server. We want to refresh the access token before it expires using the provided refresh token until the user logs out or closes the client app.

However I just cannot find any examples of how to issue this refresh token request..

To obtain the token we call something like:

curl -v --data "grant_type=password&username=user&password=pass&client_id=my_client" http://localhost:8080/oauth/token

So to refresh I'd expect the call to look like this:

curl -v --data "grant_type=refresh_token&access_token=THE_ACCESS_TOKEN&refresh_token=THE_REFRESH_TOKEN" http://localhost:8080/oauth/token

or maybe

curl -v -H "Authorization: Bearer THE_ACCESS_TOKEN" --data "grant_type=refresh_token&refresh_token=THE_REFRESH_TOKEN" http://localhost:8080/oauth/token

But it will just give me a 401..

Oh yeah, maybe I need to add the clientId? I cannot use the client secret, because there is none (see above request to obtain the token). Authentication is done using username and password after all..

I think we have the server configuration right, so I'll not post it here. If one of my example requests should work and you need to see the important config parts I'll add them.

Thanks!

Answer 1

So as I said, we don't use a client secret, because we cannot have that hanging around in the Javascript client app. And it's not needed anyway, when using the username-password grant. (See the way we request the access token). Indeed I was close to the solution and finally figured it out:

curl -v --data "grant_type=refresh_token&client_id=THE_CLIENT_ID&refresh_token=THE_REFRESH_TOKEN" http://localhost:8080/oauth/token

so no need for the access token or the client secret.

Over all it feels safe enough.

• We don't store any secret on the client app side.
• The users always need a password to log in and can only see their resources.
• We limit the validity of the refresh token to a realistic time like a workday or something so that even if it is compromised the window for an attacker is limited while still allowing the user to conveniently stay connected to the resource server throughout a long session.